BEIRUT — Syrian rebels are demanding the release of 1,000 female government detainees in exchange for the freedom of a group of Greek Orthodox nuns being held by opposition forces, according to an account published Friday in a pan-Arab newspaper.

The proposed swap indicates that the nuns are now hostages -- contradicting earlier opposition assertions that the sisters were evacuated for their own safety during heavy fighting early this week in Maaloula, a Christian landmark town outside Damascus.

Hostage-taking and kidnapping, often with sectarian overtones, have become defining characteristics of Syria’s more than 2-year-old civil conflict. The fate of two kidnapped Christian bishops, believed seized by opposition forces in April, remains publicly unknown.

[Updated at 2:50 p.m. PST Dec. 6: In a video broadcast Friday on the Al Jazeera satellite network, several of the nuns took turns speaking and appeared in good health, though it was not possible to verify the authenticity of the footage. The nuns said they had been taken for their personal safety, the Associated Press reported. Security analysts generally consider such videos to be suspect because captives may be speaking under duress.

“We are 13 nuns and three civilians and we are here in a very, very nice villa,” one of the nuns says in the video. “And we will leave in two days.”]

A spokesman for a rebel group identified as the Ahrar al-Qalamoun Brigade told the Asharq al-Awsat newspaper that the nuns would not be released until the fulfillment of several demands, most importantly the liberation of 1,000 female prisoners being held in Syrian government detention, according to the paper’s website.

“The nuns are in a safe place,” said the rebel spokesman, identified as Mohannad Abu al-Fidaa, though he declined to provide additional details.

The spokesman described the conditions for the nuns’ release as “joint demands” from his faction and another rebel group, the Nusrah Front, which is affiliated with Al Qaeda. The captors also were demanding a suspension of government sieges on a number of rebel strongholds, including several suburbs of Damascus, the capital.

Published reports have indicated that rebels seized a dozen nuns during fighting between rebel and government forces in Maaloula, a historic and mostly Christian town north of Damascus that has been the site of intense combat.

The nuns were among a community of 40 sisters said to be residing at the Greek Orthodox monastery of St. Thecla, named after an early Christian saint who was a disciple of Paul the Apostle.

Government authorities accused “terrorists” of kidnapping the nuns from the monastery at gunpoint and holding them hostage. Opposition spokesmen said the nuns were moved for safety reasons amid heavy government shelling.

The exact number of nuns taken from the monastery and whether any remained at the convent in Maaloula remained uncertain. Also unclear is the fate of as many as 21 orphans said to have been in the nuns’ care at the monastery. [Updated at 2:50 p.m. PST Dec. 6: The fate of several workers from the site also is unclear.]

The case has caused deep consternation among Christian communities in the Middle East and worldwide, with Christian and Muslim religious leaders pleading for the nuns’ release. On Wednesday, Pope Francis called for prayers on behalf of the Syrian nuns “taken by force by armed men.”

The seizure of the nuns has heightened fears among Syria’s Christian minority that they are being targeted by Islamist rebels seeking to overthrow the government of President Bashar Assad. Christians and other Syrian minorities are generally viewed as supportive of the government.

On Friday, Lebanese caretaker Prime Minister Najib Mikati contacted Syria's Greek Orthodox patriarch, John X. Yazigi, and said the abductions of the nuns “do not reflect in any way the teachings of the Islamic religion, nor do they mirror the human and spiritual values of Muslims," the Lebanese national news service reported.